Elektrochemická charakterizace oxidových vrstev vznikajících na železné elektrodě v oblasti transpasivity v koncentrovaných alkalických soustavách

Abstract

This bachelor’s thesis focuses on preparation and characterisation of oxide layer of magnetite which develops on an iron working electrode in an environment of 50 % NaOH with a temperature of 110 °C. The methods employed for the preparation of iron oxide are described in the thesis. For conducting the electrochemical experiments with increased temperature of 110 °C, the experimental apparatus was constructed with a mechanism to find the optimal setting of the furnace regulator for reaching the required temperature. An experimental probe was designed with placement of all three electrodes. The principle of micrometer screw was used for the regulation of working area environment. Oxide products were prepared by anodic oxidation of working iron electrode in the transpassive region. These products were characterised by selected electrochemical methods - method of OCP curve measurement, and method of linear voltammetry in the region of cathodic reduction. The relation between coverage of the surface of the working electrode by oxidised product and results of each electrochemical method was established. The basicity of 50 % NaOH with the temperature 110 °C for identification of stabilised phases from Paurbaix diagram was calculated. The mechanism of oxidation-reduction reaction of iron in the alkalic environment was also described.